Synchronizing device



Oct. 19, 1948.

L. c. OLSEN 2,451,691

SYNCHRONIZING DEVICE Filed May 4, 1945 F/Q. J

SPACING 22 J d1 r X. i Inventmi Attorney Patented Oct. 19, 1948 OFFICE.

SYNCHRONIZING DEVICE Leif Christian Olsen, Newcastle-.on-Tyne,

. England Application May 4, 1945, Serial No. 592,005

In Great Britain May 4-, 1944;

4. Claims. (o rise-69.5

This invention has reference to improvements in and relating to telegraphic receiving instruments, i. e., reperforators, translators, regenerators and printers, of the type wherein the changes of polarity Off the signals control synchronisation of the instrument with the received signals. One class of instrument to which the invention is applicable is that employing the Wheatstone (Morse) system of signalling.

According to the invention there is provided in telegraphic receiving instruments of the above type synchronising mechanism comprising a reversible ratchet wheel adapted to accelerate the instrument or to retard it, two single-acting, reciprocating pawls adapted to turn the ratchet wheel clockwise and anti-clockwise, respectively, and a, striker adapted to deflect either of said pawls into a position where it will engage the ratchet wheel, said pawls being adapted to reciprocate similarly and simultaneously once for each revolution of the synchronised shaft of the instrument and during their reciprocation to occupy positions where either can be subjected to pressure by the striker for causing it to engage with the ratchet wheel, each period of such occupal tion being substantially equal to half the period required by the shaft to rotate once, and said striker being adapted to be operated in one sense by signals of positive polarity and in the opposite sense by signals of negative polarity.

In thepreferred construction according to the invention the pawls comprise a dual pawl and the striker comprises a two-pronged spring tongue, said dual pawl being in the form of two spaced limbs between which is a symmetrically stepped 1 gap and the spring tongue entering the gap in a plane substantially at right angles to the plane of the dual pawl, deflections of the tongue whilst the latter is in the wider portion (the unstepped portion). of the gap being ineffective to deflect the pawl into a driving position in relation to the ratchet wheel which ratchet wheel is located in the wider gap) and tongue movements occurring when a prong is in the narrower gap deflecting or tending to deflect the pawl by pressure of the prong on a step, either one prong or the other being adapted to be received by the narrower gap during part of the reciprocation of the dual pawl.

The pawl and the tongue are so set relatively that a step and a prong adapted to co-operate to cause retardation do, by occupying the position of readiness for such co-operation, determine the moment of commencement of the period during which tongue pressure on the pawl can cause aw d m h e l n ement th ran e,-

ment being suchthatthe said pressure will be produced bylatesignals. The relative setting ofthe pawl and the ratchet wheel is such that an elemental pawl and a flank of a tooth of the ratchet wheel adapted to cause. acceleration of the instrument (or advance of phase) do, by their engagement, determine the moment of cessation ofthe period during which striker pressure on the pawl can cause pawl and ratchet wheel engage.- ments, the arrangement being such that the said pressure will be produced by early signals.

The preferred construction of synchronising mechanism according to the invention, the way in which the said mechanism functions and a modified striker will now be described with reference to the accompanying drawings wherein:

Fig. l is a side elevation of, the said mechanism viewed from one side of the double pawl I;

Fig. 2 is an end elevation of the said mechanism;

Fig. 3 shows the curve; of motion C of the cam and; also shows the position of the double pawl or at least' the steps thereof. in relation to a pivoted striker or spring tongue at certain successive mo-v ments (to, t1, etc). during a 360 turn of the cam; and

Fig. 4. shows a striker rigid withthe tongue of a synchronising relay.

In Figs,- 1 to. 3 the double pawl I, arranged approximately horizontally, is pivotally connected at 2 to the upper end of an arm 3. The arm is pivotally anchored at its lower end at 4 and between its ends has a cam follower 5. The follower lies in a groove in a cam 6 on the synchronized shaft l of the receiver. The receiver when in synchronism with perfect signals rotates once for each complete. dot (i. e., half a revolution for each signal unit or impulse). and the cam groove profile. is such that the lever oscillates once per revolution of the shaft and produces a corresponding to and fro movement of the double pawl I. From point ii to point it (Fig. 3) the pawl makes an outstroke moves to the left, Figs. 1 and 3) and from point, is to point 154 the pawl makes an instroke (moves to the right). 5

The double pawl is symmetrical about its axis. It is forked and each limb 8 which comprises an elemental pawl is stepped at 9 and terminates in an inwardlyv directed pallet l0, the pallets being opposite each other. The treads 9 and 9 of the stepsare straight and parallel and so are the inner. edgesle and 8 of the limbs 8, said treads and edges also being in parallel planes. Within the gap H between the limbs of the pawl is a Sq are. tco e rawhetwh e amet of the ratchet wheel is slightly less than the distance between the peaks of the, pallets so that the pallets whilst reciprocating just clear the ratchet wheel when they are located symmetrically in relation thereto. The said wheel is so positioned, however, and the pallets so set that deflection of the pawl upwardly or downwardly causes the lower or upper pallet to engage a tooth on the ratchet wheel and turn the said wheel anti-clockwise or clockwise through the pitch angle of its teeth provided the deflection occurs during a certain phase of the pawl reciprocation. The said phase commences at is and ends at 151- these points being about 180 apart. During the interval h to is the pallets, even if they were deflected, could not make driving engagement with the ratchet wheel as during the said interval each is either moving away from the relevant flank of a wheel tooth or is moving towards it in the non-driving sense.

The ratchet wheel is connected to a device which corrects the phase and/or the speed in a manner well known in the art, so that turning of the wheel in one direction causes the phase to be advanced and/or the speed to be increased and turning in the opposite direction causes retardation.

The said deflection of the pawl is effected by a striker comprising a centrally split spring tongue [3 the outer end of which enters the gap I I between the limb 8 at right angles to the plane of the pawl. The tongue is stifi. in the direction of its plane but the prongs thereof are readily flexible in a direction at right angles to the said plane. The height of the'portion lying in the gap is, minus a small tolerance, equal to the height of the edge 8 in relation to the tread 9 which latter dimension is equal to the depth of the edge 8 in relation to the tread 9 as will be appreciated. Moreover, the narrow end Il of the gap II is sufiiciently wide to accommodate either of the prongs of the tongue when the other prong is deflected by engagement therewith of a riser of one of the steps in a manner to be explained. The spring tongue is so positioned that the steps 9 are clear of it during the time the double pawl is at the middle of either stroke (points is and ts) and is at the right hand side (according to Figs. 1 and 3) of the mid position of stroke.

The said tongue is oscillated on a pivot M by means of the tongue l5 of a synchronising relay, not shown, the relay tongue being coupled to the tongue l3 by a pin and slot connection Hi. The relay tongue is moved in one direction by spacingmarking signals and in the opposite direction by marking spacing signals in the usual way. The limit of up and down movement of that part of the tongue in the gap H is indicated by 00, stops ll effective on the tongue defining the limits of as.

OPERATION In accordance with Fig. 3 spacing-marking signals (S-M) depress the spring tongue I3 and marking-spacing signals (M-S) lift it.

No signals arriving One edge of the spring tongue rests on an edge 8 or 8 and as the pawl I reciprocates one step flexes a prong of the tongue, the pallets I0 being pushed into the median (and inoperative) position in relation to the ratchet wheel by the action on them of either the top teeth or the bottom teeth of the ratchet wheel as they make an outstroke. The pallets are held in this position by of the receiver.

contact of the upper prong either with the edge 8 or with the tread 9 and this is one of two reasons why the steps 9 are provided, the tongue travel is limited to a: and the tongue has the previously specified height (the height which is equal to 8*, 9 or 9*, 8

Signals arriving in perfect synchronism may be received without affecting the ratchet wheel. The said zones may be reduced to zero or altered by altering the position of the pivot 2 (and the pawl) in relation to the ratchet wheel and/or by moving a back stop, not shown, for the double tongue so that the position of the said tongue is altered in relation to the steps 9.

Signals arriving too early An M-S signal arriving before is will lift the tongue I3 without having any effect on the pawl since the lower step 9 will not have reached the plane of the tongue. The upper prong of the tongue will be flexed and the lower tongue will rest on the tread B as the tongue continues its outstroke after ts. The next signal, an S-M signal, will arrive after is but before t1. Therefore the tongue, by pressure on the step 9* will depress the pawl and will hold it so owing to the persistence of the signal. Then, just before the point 131 the upper allet will engage with the immediately adjacent flank of a ratchet wheel tooth and will turn the wheel clockwise, i. e., in the direction producing acceleration of the receiver. At is the steps will move clear of the tongue.

When the receiver and the signals are synchronous turning of the ratchet wheel will cease.

Signals arriving too late An SM signal arriving after t1 will tend to depress the pawl but the pawl will meet the top of the ratchet tooth and, therefore, pawl depression will be prevented. Depression of the tongue will, however, take place at is as at this point the steps are just clear of the tongue. After it the lower step 9 will flex the lower prong of the tongue and the upper prong will lie immediately adjacent the tread 9 The next late M-S signal arriving after is will lift the tongue and, therefore, the pawl and, owing to the persistence of the signal, the lower pallet It will be held up. Just before 261 the said pallet will engage the left hand flank of the lower tooth in its path and the ratchet wheel will be turned in the direction causing retardation. Step by step turning of the ratchet wheel will be effected in this manner until such time as successive signals arrive between t1, t2 and is, is respectively.

From the above it will be clear that the upper pallet and the corresponding flank of a ratchet wheel tooth are arranged to co-operate to terminate the period ts, i1 and early S-M signals are arranged to be efiective in causing these two elements to engage so as to accelerate the receiver whereas commencement of the period is, 151 is arranged to be dependent on the co-operation of the upper step 9 and the spring tongue and late M-S signals are arranged to be effective to cause these two elements to control retardation In the former case advantage is taken Of the time in hand of early signals.

In the case of late signals no such advantage is available so the upper step 9 in association with the spring tongue is provided as described in order to produce a condition in advance of ti wherein late signals can be utilised to bring about retardation.

It will be understood that signals normally persist after each spring tongue deflection. If this were not so the ratchet wheel teeth might well nullify the effect of a late signal by restoring the outstroking pawl to its median position. On the other hand persistence of synchronous signals occurring between t5, to must not hold the pawl deflected as this would cause the pawl to turn the ratchet wheel. Moreover, I arrange that the effect of a late signal occurring after its can be nullified in relation to the pawl by a consecutive early signal. It is for these reasons and for holding the pawl in the median position whilst no signals are being received that the steps are provided, the depth of the tongue part in the gap is equal to 9 9 as previously described and the stroke of the tongue is limited to the distance :0, the steps dividing the gap ll into two sections one of which lies between the edges 8 and 8 and the other of which lies between the steps 9. When a prong is resting on a step deflection of the tongue towards the step produces movement requisite for synchronising; when the prongs are in the wider section of the gap tongue movements are lost, the condition which must obtain to ensure that signals arriving between is and ts cannot, by holding the tongue deflected, also hold the pawl deflected; and when a late signal occurring after ts is succeeded by an early signal the lower prong by pressing on the edge 8 restores the pawl to its median position-thereby nullifying the effect of the late signal on the pawl.

It may be explained that in the event of the order of the signal arrivals being reversed in relation to the positions of the pawl shown in Fig. 3 asynchronous signals will cause the instrument to hunt until the signal arrivals are in correct relationship to the said positions of the pawl.

The spring tongue instead of being pivoted as shown in Fig. 2 may be rigid with the relay tongue. The latter form is shown in Fig. 4. The tongue I8 in Fig. 4 comprises a blade which is centrally split at one end, this being the end which is to enter the gap II in the dual pawl I, and is fixed at its other end to the relay armature IS. The said armature is pivoted at 20 in the usual way; the relay pole pieces are indicated at 2i and stops which limit the tongue travel to :c, Fig. 3, are indicated at 22.

WhatIclaim is:

l. A telegraphic receiving instrument comprising a ratchet wheel adapted to accelerate or retard a synchronized shaft of the instrument according to the direction in which the wheel is turned, a dual pawl comprising two spaced limbs with asymmetrically spaced gap therebetween, providing a wider gap portion and a narrower gap portion, means to reciprocate said pawl in timed relation to said shaft and signal responsive means including a two-pronged spring tongue entering the gap in the pawl at right angles thereto one of said prongs being flexed on such reciprocation and the other of said prongs entering the narrower gap portion, the actuation of said signal responsive means determining the path of the pawl during reciprocation to apply correctional movement to the ratchet wheel in the event of signals arriving out of synchronism.

2. A telegraphic instrument according to claim 1 and comprising signal responsive means and a cooperating dual pawl in such relative arrangement that in-synchronism signals cause the pawl to travel in a path which clears the ratchet wheel, whereas out-of-synchronism signals arriving late predispose the pawl to take a different path which rotates the ratchet wheel so as to retard the instrument.

3. A telegraphic instrument according to claim 1 and comprising a signal responsive means and a cooperating dual pawl in such relative arrangement that in-synchronism signals cause the pawl to travel in a path which clears the ratchet wheel, whereas out-of-synchronism signals arriving early modify the path of the pawl to engage the ratchet wheel so as to rotate the ratchet wheel to advance the instrument.

4. A telegraphic instrument as claimed in claim 1, comprising a pawl having Wider and narrower gap portions and a two-pronged spring tongue adapted to occupy either mark or space positions, said tongue in the space position and with one prong in the narrower gap and the other prong in the wider gap, sets the pawl in a non-engaging position in relation to the ratchet wheel or alternatively, in the same position, sets the pawl in one engaging position but with the other prong in the narrower gap and the first-named prong in the wider gap.

LEIF CHRISTIAN OLSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,931,876 Salmon Oct. 24, 1933 FOREIGN PATENTS Number 9 Country Date 240,906 Great Britain 1925 308,672 Great Britain 1929 

